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# How to set a quartz crystal for series and parallel resonant mode ?

Dear All
Hi
Thank you for reading my blogs .
As it was my question for long times , and as i understood it is question of many of peoples , when i found it's answer i have decided to put it as simple as possible here . and before that i want say thank you very much to my best friends that helped me to understand it .
Well lets start : we have a Crystal , it is a mechanical element but according to the behavior of this element we can model it with electrical circuits ( as we can model each thing in this world with electrical circuits , even a building or a tree ! or a fish ! )
It's behavior is as a 2nd order network with very large Q ( pretty narrow band ) See below , please :
https://s3.picofile.com/file/7497287197/quartz.jpg

A crystal can works at it's fundamental component or at as an overtone ! it means it can works at other harmonics ( usually 3rd and 5th and 7th ... ) but with lower amplitudes but with good precision and stability ! it depends on your circuit .
A crystal will have two mode of operation :
1- series resonant mode . series mode means at resonant frequency it will appear as a short circuit .
2- Parallel resonant mode . parallel mode means at resonant frequency it will appear as an open circuit .
But it is possible that now you ask yourself how we can set our crystal in series mode or parallel mode and what is the benefit of each mode ?! now i'm going to tell you !
See below , please :
Parallel resonant :
https://s3.picofile.com/file/7497321177/parallel_resonant.jpg
and an oscillator with this effect :
https://s3.picofile.com/file/7497321505/parallel_resonant_otscillator.jpg
Series resonant :
https://s3.picofile.com/file/7497324187/series_resonant_mode.jpg
and an oscillator with this effect :
https://s3.picofile.com/file/7497323117/series_oscillator.jpg

Have nice time ! and enjoy from your oscillators ! i will come back !
Goldsmith

Thats a nice blog thank you. can you elaborate them more with couple of practical examples in another blog. This would help readers in real life designs.

Hi dear I_think
can you elaborate them more with couple of practical examples in another blog. This would help readers in real life designs.
Sure , my next blog will be about it ! i promise !
Good luck
Goldsmith

Nice blog. Very helpful.

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goldsmith